Ultrasonic transducer scanning system



Oct. 22, 1968 PH ET AL 3,406,564

ULTRASONIC TRANSDUCER SCANNING SYSTEM Filed Sept. 13, 1965 RESOLVER glaTRANSDUCER i ure STEPPING MOTOR RICHARD B. OSGOOD (2.0 swxxk ATTORNEYUnited States Patent 3,406,564 ULTRASONIC TRANSDUCER SCANNING SYSTEMEdward H. Phillips and Richard B. Osgood, Los Altos, Calif., assignorsto Hewlett-Packard Company, Palo Alto, Calif., a corporation ofCalifornia Filed Sept. 13, 1965, Ser. No. 486,969

12 Claims. (Cl. 7367.8)

ABSTRACT OF THE DISCLOSURE An oscillatory mass including an ultrasonictransducer is supported on a chassis mounted for movement along anarcuate scanning path. A torsion spring coupled at one end to thechassis and at theother end to the oscillatory mass provides theoscillatory mass with a natural frequency of oscillation. The energylost by the oscillatory mass during oscillation is supplied by astepping motor. A resolver continuously indicates the position of thetransducer during oscillation of the oscillatory mass. An electricalpulse source energizes the transducer to send ultrasonic energy to abody being scanned. The ultrasonic energy reflected back from this bodyis received by the transducer and applied to a utilization circuit forrelation to the time domain.

This invention relates to an ultrasonic transducer scanning apparatusfor scanning a body under test in a mechanically oscillating mode.

It is the principal object of this invention to provide a scanningsystem wherein a transducer sends and receives ultrasonic energy in amechanically oscillating mode.

In accordance with the illustrated embodiment of this invention there isprovided a scanning system wherein a torsion spring and a rotating mass,including a transducer for sending and receiving ultrasonic energy aremechanically coupled to provide a resonant system. This resonant systemis driven by a stepping motor to oscillate the transducer as thescanning system moves along a selected scanning path. The electricalstepping motor supplies the energy dissipated by the rotating mass andother moving elements of the scanning system, and a resolvercontinuously provides accurate positioning information during theoscillations of the transducer.

Other and incidental objects of this invention will become apparent froma reading of this specification and an inspection of the accompanyingdrawing in which:

FIGURE 1 is a schematic View of a scanning system according to thepreferred embodiment of this invention; and

of this invention.

Referring to FIGURE 1, there is shown a scanning system for sending andreceiving ultrasonic energy in a mechanically oscillating mode as thesystem is moved, for example, in an aqueous medium 12 along an arcuatepath 14 to scan a body 16 under test. The body 16 under test may eitherbe emersed in the aqueous medium 12 as shown in FIGURE 1 or separatedfrom it by a thin membrane. This scanning system comprises a transducer18 having a piezoelectric crystal 20 which deforms momentarily, whenpulsed by an input signal from pulse source 21, to generate a highpressure acoustical wave 22 which is transmitted through the aqueousmedium 12 to the body 16. An acoustical wave 24, which is reflected fromthe body 16 because of an acoustical impedance mismatch between the body16 and the aqueous medium 12, momentarily deforms the piezoelectriccrystal 20 as it is received thereby. This deformation of thepiezoelectric crystal 20 by the reflected acoustical wave 24 causes thepiezoelectric crystal to generate a corresponding electrical FIGURE 2 isa schematic view of another embodiment 3,406,564 Patented Oct. 22, 1968signal which is applied to a utilization circuit 25 where it is relatedto the time domain to convey desired information about the structure ofthe body 16. The information that may be obtained about the structure ofthe body 16 is maximized since the transducer 18 oscillates as thescanning system moves along the arcuate path 14 so that thepiezoelectric crystal 20 generates high pressure acoustical waves over awide range of angles with respect to the body 16. Thus, thepiezoelectric crystal 20 receives reflected waves from skew surfacesand, hence, information that would otherwise be lost.

The oscillating mode of operation of the transducer 18 is provided bymechanically coupling a torsional clock spring 26 to a rotating massincluding the transducer 18 and all other elements of the scanningsystem which are rigidly coupled to the shafts 28 and 30 for rotationtherewith. The clock spring 26 is supported on the shaft 28 with one endbeing attached to shaft 28 and the other end being attached to thechassis 32 on which the rotating mass is mounted. The natural resonantfrequency f,- of the clock spring 26 and the rotating mass isapproximately equal to /z1r /K/I, where K is the torsional springconstant of the clock spring 26 and I is the momentof inertia of therotating mass. Less power is required to oscillate the transducer 18when it is driven in an oscillating mode at or near this naturalresonant frequency f A stepping motor 34 is mechanically coupled to theshaft 28 by gears 36 and 38 which are mounted on shafts 28 and 30,respectively, to engage one another with a one to one gear ratio. Thisstepping motor 34 is driven to supply the energy dissipated by therotating mass as it oscillates in the aqueous medium 12 and by thefriction forces exerted on the other moving elements of the scanningsystem. Although the stepping motor 34 is normally driven by an inputsine-wave signal having a frequency of oscillation approximately equalto the resonant frequency f,., the amplitude and frequency ofoscillation of the input sine- Wave signal may be varied toalter theamplitude and frequency of oscillation of the rotating mass. A resolver40 is also mechanically coupled to the shaft 28 to contin uously providean accurate indication of the position of the transducer 18 during eachmoment of the mechanical oscillation thereof.

Referring now to FIGURE 2, there is shown another way for providing theoscillating mode of operation of the transducer 18. One end of a bartorsion spring 26 is attached to the rotating mass including the shaft28 and the transducer 18. The other end of the bar torsion spring 26 isattached to be driven by the stepping motor 34 which is mounted on thechassis 32. Resolver 40 is coupled to the shaft 28 for continuouslyindicating the position of transducer 18 during the mechanicaloscillation thereof.

We claim:

1. In an ultrasonic transducer scanning apparatus adapted for movementin a fluid along a selected path to scan a body under test fordetermining a selected characteristic thereof:

an oscillatory mass being supported by a chassis therefor and includinga transducer for sending ultrasonic energy to said body and receivingback reflections therefrom;

a signal source connected for energizing said transducer and causing itto send said ultrasonic energy;

a utilization circuit responsive to the reflections from said bodyreceived by said transducer to relate said reflections to the timedomain;

a torsion spring having one end coupled to said chassis and the otherend coupled to said oscillatory mass to provide said oscillatory masswith a natural frequency of oscillation;

means coupled to said oscillatory mass for supplying the energy lost bythe oscillatory mass during mechansaid oscillatory mass including atransducer for receivical oscillation thereof; and r ing energy; a I I aresolver coupled to said transducer for continuously a ili i i it o si tth ner received indicating the position thereof during said mechanical bid d e oscillation. I v a i v means coupled to said system for supplyingthe energy '2. 'An' ultrasonic transducer scanning apparatus for 7 1 bid illa y phasg'du ing mechanical-psscanning a body under test todetermine-a selected chard l i h gand I g I 1 fiotoristto thereof, Saidapparatus comprising! r ca resolver connected to said oscillatory mass.for inan oscillatory mass including a transducer to receivdi i h iti fsaid transducer during the ing ultras rgy; 10 mechanical oscillationthereof. 'a utilization circuit responsive to the ultrasonic en- 3 Atransducer a ing apparatus f scanning a y Ioooivd y S tl'ahsduool torelate the body under test tocdeterminew at selected characteristiccoivod energy to the time domain; thereof, said apparatus comprising: atorsion spring having one end coupled to a reference a 'inn p in nda lscillatoryr'mass 'operatively Plano and the other end Coupled to Saidoscillatory connected to provide a system, having a natural-ire a massto provide said oscillatory mass with a natural Y quency f ill i n; v Aq o oscillation; and i said oscillatory mass including a transducer forsendmeans coupled to said oscillatory mass for supplying i energy; fthofihofgy lost Y the oscillatory mass during moohaha signal sourceconnected for energizing said trans- I ical oscillation thereof. a ducerto send energy to said body; I

3. An ultrasonic transducer scanning apparatus as in means Coupled to iSystem f l i mea claim 2 wherein a resolver is coupled to saidoscillatory ergy lost by i ill mass during mechanical mass forindicating the position of said transducer during ill i h f; d V c themechanical oscillation of Said oscillatory massa resolver connected tosaid oscillatory mass for inv In an ultrasonic Scanning apparatusadapted for dicating the position of said transducer during the movementin a fluid along a selected path to scan a body mechanical iii i th funder test for determining a selected characteristic there- 9 Anultrasonic I transducer n i aratus for of: scanning a body under test todetermine a selected charan oscillatory mass being supported by achassis thereacteristic th of id apparatus comprising:

for and including a transducer for sending ultrasonic an oscillatorymass including a transducer f d. energy to said body and receiving backreflections V H ing ultrasonic energy; 7 r v thorotrom; a signal sourceconnected to said transducer for enera signal source connected forenergizing said transducer g'izing it to e ultrasonic energy to id body;

and causing it to Send Said ultrasonic energy; a torsion spring havingone end coupled to a refera utilization circuit responsive to thereflections from ence plane and the other end coupled to Said ilsaidbody received by said transducer to relate said iatory mass to id idoscillatory mass with reflections t0 the time domain; a naturalfrequency of oscillation; and a a toroioh Spring having one end attachedto Said means coupled to said oscillatory mass for supplying tatlhgmass; the energy lost by said oscillatory mass during memeans mounted onsaid chassis and coupled to the other 40 i l ill i h f r d of saidtorsion Spring for pp y the energy a 10. An ultrasonic transducerscanning apparatus as lost y said oscillatory mass during mechanicalosoflla in claim 9 wherein a resolver is coupled to said oscillatiOHthol'oof; and tory mass for indicating the position of said transducer 3{esolvel o lf t to Said ot y during the mechanical oscillation of saidoscillatory mass. tlnuously indicating the posltlon of said transducer11 An ultrasonic transducerv scanning aratus for s igfl lmoohaflioaldosoillatioh thefooff scanning a body under test to determinea selected char- 11 tfasohio trails hoof Scanning apparatus oracteristic thereof, said apparatus comprising: i o zh gl g hc l test tdetormiho a Selooted oharao' an oscillatory mass includinga transducerfor sending @Ils 1c -l'e0 Sal appara 13S COmpl'lslng: I ultrasonicenercy;

all li o 'y mass lholhdlng a transducer for Tooolvlhg a signal sourceconnected to said transducer for encr- 11 rasohlo y; gizing it to sendultrasonic energy to said body; a utilization circuit responsive to theultrasonic energy a torsion spring having one end attached to saidreceived by said transducer to relate the received 7 ciuatol-y mass; andf y to t o domain; means mounted on a reference plane and coupled to atfrswn sprmgllaavlng one end attached to said osclllaother end f saidtorsion spring f supplying mass; on the energy lost by said oscillatorymass during memeans mounted on a reference plane and coupled to the Vchanicai oscillation thereon other end of l totsloh sPrmg for PP Y v 12.An ultrasonic transducer scanning apparatus as in f y l by Soldosoluatol'y mass durlhg meohahloal claim 11 wherein a resolver iscoupled to said oscillatory oscluatlon F o v mass for continuouslyindicating the position of said trans- An ultrasomc transducer scanmngplg s as m ducer during the mechanical oscillation of said oscillatoryclalm 5 wherein a resolver is coupled to said oscillatory mass, mass forcontinuously indicating the position of said 7 Ref rences Cit dgztilrssrgzgsdurmg the mechanical oscillation of said oscll- UNITEDSTATES PATENTS v 7. A transducer scanning apparatus for scanning a body8 9 4/ 9 3 B Wn 73-673 under test to determine a selected characteristicthereof, 3,308,652 3/ 1967 pp ot i said apparatus comprising:

a torsion spring and an oscillatory mass operatively RICHARD QUEISSERPrlmary Exammer' connected to provide a system having a natural 'fre-JOHN BEAUCHAMP, Assistant Examiner. r quency of oscillation; t

